Conventional automotive vehicles typically include a brake pedal that is operatively connected to a brake lever or arm. The motion of the brake arm in turn actuates a braking mechanism to thereby slow and/or stop the vehicle, typically using an applied hydraulic pressure. For example, stepping on a brake pedal exerts a force on a master cylinder, which then pressurizes various hydraulic lines that supply the pressurized fluid to the various brake corners, i.e. each of the wheels of the vehicle. At each brake corner, the pressurized fluid powers an actuator, such as a piston, which forces a friction surface of a brake pad against a rotating brake drum or disc. The rate of deceleration imparted to the vehicle depends on the amount of force originally applied to actuate or depress the brake pedal, and on the travel position of the brake pedal within or along its range of motion.
By way of contrast, a by-wire or electronic braking system (EBS) is often used in electric vehicles, as well as in hybrid vehicles which are alternately and selectively powered by an internal combustion engine or fuel cell and one or more electric motor/generators. Using an EBS, the braking command or input applied as a force to a brake pedal by an operator of the vehicle is converted by an encoder device into an electrical braking signal. This electrical braking signal, also known as an electronic braking torque request, is then relayed or communicated to the point of application, where one or more brake actuators operate in response to the communicated signal to slow or stop the vehicle.
Total braking torque in a vehicle having both an EBS and a conventional braking system may be applied using a blended combination of friction braking mechanisms and electronic braking torque, the latter of which is usually applied as an opposing torque to a braking unit positioned in proximity to each wheel, and/or to a transmission output shaft, thereby slowing the vehicle in a precisely controlled manner. However, the difficulty in precisely combining conventional friction braking and electronic braking torque may result in a less than optimal smoothness and/or continuity of such a blended braking event.